Steam boiler control



Sept. 18, 1945. J. L. PHSIKERTON 3 5 STEAM BOILER CONTROL Filed Dec. 10, 1940 VIII/III!! 5 wn'M E55 ATTORNEYS Patented Sept. 18, 1945 UNITED STATES PATENT OFFICE STEAM BOILER CONTROL Jack L. Pinkerton, Long Beach, Calif. Application December 10, 1940, SerialNo. 369,473

2 Claims.

My invention relates to the regulation of water levels in steam boilers and the like, and includes among its objectsand advantages the provision of an improved controller designed to maintain predetermined levels in the boiler, to signal when the water level reaches a predetermined second low level, and to cut off the delivery of fuel to the boiler in the event that. the water level drops toa dangerous or predetermined third low level.

In the accompanying drawing:

Figure 1 is a diagrammatic illustration of the electric circuit illustrating, structurally, the manner in which the circuit elctrodes are supported for coaction with the water; and

Figure 2 is a sectional detail View of one of the electrodes. 7

In the embodiment selected to illustrate my invention, I make use of a tubular member I arranged vertically and provided with flanges I2 at its ends for connection with flanges I4 on the ends of pipes I6 and I8 which have communication with the steam boiler (not shown). The body I0 is located on the steam boiler in a position equivalent to the location of the water glass, so that normal water levels which would appear in such a glass would also rise to positions inside the member I0.

'I'hree electrodes 20, 22 and 24 extend horizontally inside the member I0. Fig. 2 illustrates the specific construction of the electrode 20 I and, since all the electrodes are similar in construction and operation, the description of one will apply to all. The sleeve 26, inside which the electrode 20 is secured, is partially enclosed inside a shell 28 having a threaded shank 30 threaded into the opening 32 in the member I0. Sleeve 26 preferably comprises glazed porcelain and is provided with a'shoulder 34 against which is seated a sealing element 36 lying against a shoulder 38 in the shell 28. A sealing element 40 is interposed between the shell 28 and the member 20 so as to provide a liquid and pressure tight connection between the electrode structure and the member I0. The exterior end 42 of the electrode includes a flange 44 anda nut 46 threaded on the end 42 so that a lead may be clamped between the flange and the nut,

In Fig. 1, the electric circuit includes three control circuits 48, 50 and 52 respectively associated with the electrodes 20,22 and 24. Three operating circuits 54, 56 and 58 are respectively associated with the control circuits 48, 50 and 52. The current supply lines 60 and 62 are connected with the primary winding 54 of a transformer 66, and the secondary windings 68, 10 and 12 are respectively connected with theelectrodes. 20, 22 and 24 through the medium of leads 14, .16 and 18. Leads 80, 82 and 84 respectively connect the secondary windings 68, 10 and 12 with relays 86, 88 and respectively included in the control circuits 48, 50 and 52.

In the control circuit 48 is a vaeuumtube 92 having its filament 94 connected with the secondary winding 68 by a lead 96, which lead is grounded at 98. A lead I00 connects the filament 94 with the lead 14, and a lead I02 connects the grid I04 with the lead 14, the latter having a cohdenser I06 interposed therein between its connection with the leads I00 and I02.

The plate I08 of the vacuum tube 92 is connected with a lead IIO connected with the relay 86, and a condenser H2 is connected across the leads and H0, with the screen grid H4 connected with the lead 80 through the medium of a lead H6. The control circuits 50 and 52 are also each provided with a vacuum tube 92, all of whichtubes are identical and well known in the art. Since the circuit 48, 50 and 52 are identical in all respects, the reference numerals applied to the tube 92 and its wiring in the circuit 48- are similarly applied in the circuits 50 and 52.

The armature II8 associated with the relay 86 is connected with a lead I20 and is normally spaced from a contact I22 connected with a lead I24. Lead I20 connects with a relay I26 having its second lead I28 connected with a secondary winding I30 of the transformer 66. A lead I32 connects the secondary winding I30 with the lead I24, and a lead I36 connects the lead I32 with the armature I38 of the relay I26. Armature I38 is normally spaced from a contact I40 connected with a solenoid coil I 42 which, when energized, serves to open a water supply valve I44, which valve is normally closed. Solenoid coil I42 is connected with the secondary winding I30 by a lead I46.

A lead I48 connects the armature I50 of the relay 88 with an alarm relay I52 having its second lead I54 connected with a lead I56 connected with the secondary winding I30. A lead I58 connects the lead I32 with the armature I60 of the alarm relay I52, which armatureis normally spaced from a contact I62 connected .with an alarm I64 having its second wire I66 connected with the wire I56.

A lead I68 connects the armature I10 of the relay with a fuel cut-off relay I12 to the armature I14 of which is connected the wire I32. Armature I14 is normally spaced from a contact I16 connected with a solenoid coil I18 which,

when energized, serves to close a fuel cut-01f valve I80. The solenoid coil I'I8 has its second Wire I82 connected With the wire I56, the latter serving as the second wire for the relay I I2. The contacts I84 and I86 of the relays 8B and 90, respectively, are connected with the wire I24.

The valves I 44 and I80, together with the alarm I64, which may be of the audible or visible type are well known in the art and need not be ex plained in detail. Suffice it to say that the valve I44 is normally closed and opens only when the water in the boiler reaches a predetermined low level. Also, the fuel cut-off valve I 80 is closed only when the Water in the boiler reaches a predetermined third or dangerous low level. Member I8 is grounded at I88.

The leads I4, I6 and 18 are respectively connected with the grid circuits of the vacuum tubes 92. Fig. 1 illustrates the liquid level at I99, at which time the electrodes 22 and 24 are submerged in the liquid while the electrode 20 is partially submerged. So long as the electrode 20 makes contact with the water or other conducting fluid in the member It], the grid circuit of the vacuum tube 92 in the control circuit 48 is effectively shorted to cathode, removing the bias and causing the tube to draw suflicient current to close the relay in its plate circuit so that the armature IIB will normally take the position of Fig. 1. If, however, the water level in the member I descends until the electrical circuit of the electrode 20, the water and the metallic body is broken, then the grid of the vacuum tube 92 is open, or floating, and no current will flow in the plate circuit. The relay 86 then releases the armature II8 for engagement with the contact I22. When such contact is established the circuit will be closed through the relay I26, which moves the armature I38 into engagement with the contact I 40 for energizing the solenoid coil I42 for opening the water supply valve I44.

With the water supply valve I44 open, water will rise in the boiler until it again makes con tact with the electrode 20, which again causes energization of the relay 86 to move its armature I I8 out of engagement with the contact I22 so as to break the circuit through the relay I26 and deenergize the solenoid coil I42 so that the water supply valve I44 may close.

As long as the circuit relating to the water supply valve I44 operates in a normal manner, the level of the water in the boiler will be automatically maintained. In the event of failure of any part of this phase of the system, the Water level in the boiler drops below the electrode 22. Such low level of the water will cause deenergization of the relay 88 so that its armature I58 will engage the contact I84 for closing the circuit through the relay I52. With the relay I52 energized, th armature H6 is pulled into engagement with the contact I62 so as to close the circuit through the signal I64. Thus the attendant is warned that the water in the boiler has dropped below the safe level normally maintained by the control circuit 48. If the boiler is then attended, and the water replaced to the required level, the system will be restored to normal, but if the water is not replaced and the system not repaired, continued lowering of the water level in the boiler finally bringsthe level below the electrode 24. Under such conditions, the relay 90 will be deenergized to release the armature I ID for engagement with the contact I86, which closes the circuit through the relay I12. Energization of the relay I12 moves the armature I14 into engagement with the contact I16 to close the circuit through the solenoid coil I78, so that the fuel cut-off valve I will be actuated to cut ofi the supply of fuel to the boiler. Thus the fire will be extinguished and the boiler protected from damage. It is preferred that the fuel cut-off valve I80 be of the locking type, so that when once the valve has been closed because of a low water condition in the boiler, it will not reopen electrically but must be opened manually by the attendant after the water level has been restored in the boiler.

The system is extremely sensitive in its operation. A change in the waterlevel as small as one-sixteenth of an inch will bring the control circuit 48 into action for opening the supply valve I44. The glazed porcelain sleeves of the electrodes prevent corrosion and effectively insulate the electrodes from the body of the member ID. The electrodes 28,722 and 24 are positioned horizontally. When the waterv level in the boiler reaches the level of the electrode, the circuit which that electrode controls will be immediately made, or when the water descends below that level, the circuit will be instantly broken, thus allowing a relatively small differential in the water level between the times that the circuit is made and broken. The porcelain sleeves associated with the electrodes are capable of withstanding extreme temperatures and pressure conditions without damage or deterioration over long periods of time.

Without further elaboration, the foregoing will so fully illustratemy invention that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

I claim: V I

1. In a steam boiler: an electrode located for contact with the water in the boiler at its normal level therein; said boiler being grounded; an electrically operated water supply valve and an operating circuit therefor; a vacuum tube connected with a source of current and having its grid circuit connected with said electrode to energiz the plate circuit of the vacuum tube through contact between said electrode and the water in the boiler; said vacuum tube having a grounded filament; a relay connected into said plate circuit; and a switch connected into said operating circuit and biased to an open position by the energized relay, but moving toa closed position upon deenergization of the plate circuit and the relay when the water in the boiler moves out of contact with said electrode, to open said water supply valve. v I p 2 The invention described in claim 1 wherein said electrodeis positioned horizontally.

JACK L. PINKERTON. 

